Abstract

This field trip explores the role of geology in the origins and production of a distinctly American distilled spirit. Bourbon whiskey originated in the late 1700s and early 1800s in the Bluegrass region of north-central Kentucky. The Inner Bluegrass is marked by fertile, residual soils developed on karstified Ordovician limestones. Corn was grown, ground, fermented, and distilled to yield a high-value product that would not spoil. The chemistry of limestone water (dilute calcium-bicarbonate type with near-neutral pH) limits dissolved iron and promotes fermentation. Many farms and settlements were located near perennial springs, whose relatively cool temperatures (~13–15 °C) facilitated condensation of steam during distillation. We will visit three historically significant springs. Royal Spring in Georgetown was an early site of whiskey production and is one of the few springs in Kentucky still used for municipal water supply. McConnell Springs was the purported site of Lexington’s founding and occupies a karst window in which distilleries once operated. Cove Spring in Frankfort was the site of the first public water supply west of the Allegheny Mountains. We will also tour two distilleries: Woodford Reserve (among the oldest and smallest in the state, and a National Historic Landmark) and Four Roses (listed on the National Register of Historic Places).